Update README with installation and usage info

Author: mattlink

README.md

@@ -1 +1,68 @@
-![pyrexpaint-logo](https://user-images.githubusercontent.com/9204112/150735182-551ebe2d-882e-4c46-ab44-1dcbc7cb9751.PNG)
+![pyrexpaint-logo](https://user-images.githubusercontent.com/9204112/150735182-551ebe2d-882e-4c46-ab44-1dcbc7cb9751.PNG)
+
+
+# Details
+`pyrexpaint` is a small API for loading .xp files into python programs. So small, there is a single function provided called `load`.
+
+An .xp file is the custom binary format used by the ASCII art editor [REXPaint](https://www.gridsagegames.com/rexpaint/index.html).
+
+
+# Installation
+
+
+```
+pip install pyrexpaint
+```
+
+or install from source:
+
+```
+git clone https://github.com/mattlink/pyrexpaint
+```
+```
+pip install ./pyrexpaint
+```
+
+# Usage
+
+Say you have an .xp file `hello.xp` in the same directory as your program, it can be loaded using:
+```
+import pyrexpaint
+image_layers = pyrexpaint.load("hello.xp")
+```
+
+The data structure returned by `load` is as follows:
+```
+
+@dataclass
+class Tile:
+    ascii_code: str
+    fg_r: str
+    fg_g: str
+    fg_b: str
+    bg_r: str
+    bg_g: str
+    bg_b: str
+
+
+@dataclass
+class ImageLayer:
+    width: int
+    height: int
+    tiles: List[Tile]
+
+
+def load(file_name: str) -> List[ImageLayer]:
+    ...
+```
+
+
+## Run the Ncurses Example:
+
+```
+cd ./pyrexpaint/examples
+```
+```
+python hello-ncurses.py
+```
+